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scratcherky Rookie Member


Joined: Jan 29, 2005 Posts: 15 Location: Bluegrass State
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Posted: Sat Jul 22, 2006 4:48 pm Post subject: Pressure Signs |
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 I am aware of too high pressure signs but I would like to know if there are any recognizeable signs of too low pressure. I am referring to bottle neck rifle rounds.
Thanks,
Don
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PaulS Super Member


Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Sat Jul 22, 2006 6:47 pm Post subject: Re: Pressure Signs |
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Lets see, dangerously low pressure signs would include:
primer prodruding from the base of the shell but still tight.
Black soot covering the case from the mouth toward the base. It might just be the neck and shoulder but it could go halfway down the case.
bullets stuck in the barrel - this one might not be readily noticed until you fire the next shot which will of course put a large bulge or logitudinal split in your barrel.
Squib loads - where the powder is pushed with the bullet into the barrel but does not burn.
Detonation - similar to the squib load but the powder stay lit and burns from several points slowly until everything comes to rest and then explodes with enough pressure that your case is destroyed and your gun could be as well.
I think that covers just about everything - at least all that my old brain can remember right now.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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scratcherky Rookie Member


Joined: Jan 29, 2005 Posts: 15 Location: Bluegrass State
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Posted: Sun Jul 23, 2006 6:27 am Post subject: Re: Pressure Signs |
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PaulS Thanks for the info. I do not think I have dangerously low pressure but on occasion I get some black soot on the case neck only about half way to the shoulder. Is this normal or does this indicate that the pressure should be increased some. I see this mainly when starting to work up a load using the low range of powder from reloading manuals.
Thanks,
Don
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Spacedone Member


Joined: Nov 04, 2005 Posts: 266 Location: missouri
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Posted: Sun Jul 23, 2006 8:16 am Post subject: Re: Pressure Signs |
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be sure to use a acceptable powder for the min loading.
rule of thumb is if the powder doesnt fill more than half the case then your using the wrong powder.
optimum is where the powder for the FPS your wanting almost completely fills the case but not enough to make you compress the charge.
saving pennies by scrimping on powder can be dangerous.
to low of pressure IS MORE dangerous than to much.
a gun designed to taqke 60,000 psi actually is rated at like 80,000 psi.
to little pressure can make a detonation which may exceed the guns tolerance.
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ares Rookie Member


Joined: Mar 05, 2006 Posts: 10 Location: Czech Republic
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Posted: Sun Jul 23, 2006 9:11 am Post subject: Re: Pressure Signs |
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I think, that this is what Scratcherky thought:
sweb.cz/Ares79/lowpres/neck1.jpg
sweb.cz/Ares79/lowpres/neck2.jpg
Is that something black on the neck a sign of low pressure?
In the case there is 45,5gr of Tubal 7000 powder, so between the powder and bullet there are about 5mm of free space. The case is 7,62x54R
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scratcherky Rookie Member


Joined: Jan 29, 2005 Posts: 15 Location: Bluegrass State
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Posted: Sun Jul 23, 2006 9:57 am Post subject: Re: Pressure Signs |
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ares your first pic is what I was referring to only not as much soot and only about half way up the neck.
I choose a powder to try for about 85% of case capacity and never where there is a chance of a double load.
Thanks,
Don
_________________ Man and Man's Best Friend
Still Looking at the Green Side of Sod |
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ares Rookie Member


Joined: Mar 05, 2006 Posts: 10 Location: Czech Republic
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Posted: Sun Jul 23, 2006 10:00 am Post subject: Re: Pressure Signs |
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I think, that I have to use a faster powder
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Dimitri Super Member


Joined: Nov 25, 2005 Posts: 5942
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Posted: Sun Jul 23, 2006 11:01 am Post subject: Re: Pressure Signs |
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You know if your worried about high pressure just get a M1 Garand in testing they were rated for a 120,000 PSI proof load + being able to shoot after that. The proof load that would crack the bolt slightly still would be safe for 5,000 rounds or so
Dimitri
_________________ A thousand hills, but no birds in flight, ten thousand paths, with no people's tracks. A lonely boat, a straw-hatted old man, fishing alone in the cold river snow. |
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